Regional standard times of countries in the world are provided with time differences defined on the basis of Universal Time Coordinated (UTC). The standard times are basically provided for given regions that are mainly divided in longitudinal directions, and these regions each are called ‘a time zone.’
In this regard, according to Patent Document 1, for example, in the case where a host vehicle comes and goes between time zones or travels a road crossing over a boundary between time zones, a time displayed is performed without giving a troublesome feeling as much as possible to a driver even if the time zone is changed, such that a display unit for indicating the time is changed in color or blinked.